The low profile plastic 120VAC RV receptacles are designed to be placed in tight quarters and use the pinch type wire connections. The ROMEX is not cut off like the standard type 120VAC wiring boxes but stripped back and just layed into the fixture. Then we you press it all in place the knife type holders cuts thru each wire and makes contact. This will allow another daisy chain 120VAC receptacle further down the zone. These are not intended to be used as a junction point for additional receptacles.
Another thing to look out for is when these type of receptacles are used a small crease is put on the cable wiring and if you move it, it easily may break into. Then you gots more problems
If you have enough space you might replace the pinch type 120VAC receptacle for a PVC junction box and use a standard 120VAC house type receptacle with screw terminals. The problem of course is going to be finding enough slack in the presently used romex to do this.
Check in with LOWES electric dept and look at all the 120VAC house type items you can use to install another 120VAC receptacle
You may have to install a PVC junction where you have some slack behind your cabinet and install another 120VAC circuit using twist-on wire nut connections
Roy Ken